This is certainly a development I could get behind. It's something I would find particularly useful. If you know how to create it, then Yes Please from me.
This sounds similar to the app for symbian called best profiles.
It would be great for start if someone could create a GUI for auto profile switching from general to silent and back at predefinied time.
I'd like to suggest another feature as part of this request: toggle vibrate on/off for the profile that is set at a specific time. For example, at night, set the phone to "silent" profile and also disable vibrate.